An evaluation of the impacts of land surface modification, storm sewer development, and rainfall variation on waterlogging risk in Shanghai
An evaluation of the impacts of land surface modification, storm sewer development, and rainfall variation on waterlogging risk in Shanghai
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DOI：
10.1007/s11069-012-0153-1
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发表时间：
2012-04
期刊：
影响因子：
3.7
通讯作者：
Xiaodan Wu;D. Yu;Zhongyuan Chen;R. Wilby
中科院分区：
文献类型：
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作者：
Xiaodan Wu;D. Yu;Zhongyuan Chen;R. Wilby
尽管自1950年代后期以来不断努力升级城市雨水系统，但上海市仍然容易受到持续暴雨内涝的影响，这是由于过量的地表径流和下水道附加费，经常造成建筑物严重损坏和交通中断。快速城市化和相关的土地覆盖变化是造成内涝的主要因素。然而，目前还不清楚过去几十年降雨量变化的程度。本文研究了土地利用和土地覆盖变化，雨水管道的发展和降水的长期变化的综合影响。首先提出持续性内涝的证据。然后，我们给出了在城市化和城市的城市雨水管道系统的发展过程中的土地表面的修改帐户。统计分析表明，由于农业用地向工业、商业和居民用地的转变，径流系数增加，是导致更大的内涝风险的主要因素。特别是，对航空照片的历史分析揭示了过去几十年来河流网络的变化速度和程度。天然排水网络缩小了270公里，大大降低了城市输送多余地表水的能力。与其他研究一致，我们发现年降雨总量（宝山和徐家汇）没有显著的总体趋势。然而，季节性和月降雨强度有所增加。在日尺度上，我们发现，与20世纪80年代以前相比：（i）降水量超过25 mm（大雨）的潮湿天数增加，而降水量低于25 mm的天数减少;（ii）降水量最大值和平均值超过已知导致内涝的阈值的连续潮湿天数呈增加趋势。由于气候变化，降雨强度预计会增加，这可能会进一步加剧土地使用变化的影响，并对现有的雨水下水道系统造成更大的压力。
Despite continuing efforts to upgrade the urban storm sewer system since the late 1950s, the City of Shanghai is still vulnerable to persistent rainstorm waterlogging due to excess surface runoff and sewer surcharge, which frequently cause significant damage to buildings and disruption to traffic. Rapid urbanization and associated land cover changes are the major factors contributing to waterlogging. However, it is unclear to what extent changes in rainfall variability over the past few decades are also involved. This paper investigates the combined impacts of land use and land cover change, storm sewer development, and long-term variations in precipitation. Evidence of persistent waterlogging is presented first. We then give an account of land surface modifications during the process of urbanization and the development of the city’s urban storm sewer system. Statistical analysis suggests that the increase in runoff coefficient due to conversion of lands from agricultural to industrial, commercial, and residential uses is a major factor driving greater waterlogging risk. In particular, historical analysis of aerial photographs reveals the rate and extent of modification to river networks in the past few decades. The natural drainage network has shrunk by 270 km, significantly reducing the city’s capacity to transport excess surface flow. In line with other studies, we find no significant overall trends in annual rainfall totals (at Baoshan and Xujiahui). However, seasonal and monthly rainfall intensities have increased. At the daily scale, we find that compared to pre-1980s: (i) there has been an increase in the number of wet days with precipitation exceeding 25 mm (Heavy Rainfall) and decrease in those below 25 mm and (ii) the number of consecutive wet days with precipitation maximum and average exceeding the threshold known to cause waterlogging shows an increasing trend. Since rainfall intensity is expected to increase under climate change, this could further compound the impacts of land use changes and place even greater pressure on the existing storm sewer system.